This chapter covered a lot of information on ActionScript. Do not feel alarmed if some concepts were difficultthey are covered in more detail as you continue through the following chapters.
A few key points to remember are
Objects have three features:
Properties. Information about the object
Methods. What the object does
Events. Let Flash know when something happens with the object
Use strict data typing to help debug applications early in development.
Comment your code. If you're in doubt whether or not it's important enough to comment, comment it.
Set the preferences of the Actions panel to your liking. You are going to be using it a lot from here on out, and it should be just the way you want it.
Use code hints to help keep track of individual objects' code.